In audio systems comprising a microphone and speaker in close proximity, such as the audio system shown in FIG. 1, feedback may occur due to a feedback path between the speaker and the microphone. For example, in audio devices which implement hearing augmentation, an acoustic signal from a speaker may leak from the ear canal and be picked up by a microphone positioned close to the ear.
In audio systems which implement active noise cancellation (ANC), a feedback path is purposefully created to reduce environmental noise. However, when the loop gain of such a feedback path is greater than 1, feedback will build up leading to howling at the speaker.
Known passive feedback management techniques used to address such feedback include modifying acoustics (attenuating the acoustic feedback path) or reducing gain (attenuating the electrical feedback path). In current generation ANC headsets with talk-through, low-pass filters are typically applied so that no gain is applied above 2 kHz.
Known active feedback management techniques for hearing augmentation include feedback suppression and feedback cancellation. However, both of these techniques have drawbacks. For example, active feedback suppression may allow short bursts of feedback before suppression is applied. Additionally, active feedback suppression leads to a reduction in gain in the hearing augmentation path. Active feedback cancellation may only model a linear feedback path and is limited in its performance by reverberation.
Other feedback management techniques include techniques for reducing feedback noise, for example, by microphone signal mixing. However, microphone signal mixing may corrupt binaural or stereo cues being delivered to a user.
It is desired to address or ameliorate one or more shortcomings of known feedback management techniques, or to at least provide a useful alternative thereto.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.